From 54c4de13edfaf3b9fbc1b67d6ba384618614d59e Mon Sep 17 00:00:00 2001
From: Jonny Harris <spacedmonkey@git.wordpress.org>
Date: Mon, 25 Sep 2023 17:04:41 +0000
Subject: [PATCH] Script Loader: Replace hardcoded output of style tags with
 calls to `wp_add_inline_style`.

In this commit, enhancements have been made by replacing manually constructed style tags with calls to `wp_add_inline_style`. Previously, numerous style tags were generated and output directly in the header, resulting in redundant code and bypassing the core's style enqueueing system. This approach made it challenging for third-party developers to manage and control the output of these style tags.

To ensure backward compatibility, the following functions have been deprecated and replaced:

- print_embed_styles
- print_emoji_styles
- wp_admin_bar_header
- _admin_bar_bump_cb

Backward compatibility shims have also been added, ensuring that if these functions were previously unhooked from there actions, they will continue to not output a style tag.

However, for the following functions, conversion to use inline styles was not feasible due to the potential disruption it might cause by changing the style tag IDs, potentially breaking JavaScript functionality for a number of plugins in the repository:

- custom-background
- wp-custom

These changes improve code maintainability and enhance the flexibility and control available to developers when managing style outputs within WordPress core.

Props spacedmonkey, hlunter, westonruter, flixos90.
Fixes #58775.

git-svn-id: https://develop.svn.wordpress.org/trunk@56682 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-admin/includes/admin-filters.php       |  3 +-
 src/wp-includes/admin-bar.php                 | 55 ++++++++----
 src/wp-includes/default-filters.php           |  9 +-
 src/wp-includes/deprecated.php                | 88 ++++++++++++++++++-
 src/wp-includes/embed.php                     | 24 ++---
 src/wp-includes/formatting.php                | 48 +++++-----
 src/wp-includes/theme-templates.php           | 22 ++---
 tests/phpunit/tests/blocks/editor.php         |  2 +
 tests/phpunit/tests/oembed/template.php       |  2 +
 .../theme/wpAddGlobalStylesForBlocks.php      |  5 ++
 10 files changed, 191 insertions(+), 67 deletions(-)

diff --git a/src/wp-admin/includes/admin-filters.php b/src/wp-admin/includes/admin-filters.php
index 8e3da338c5..b5adb946cf 100644
--- a/src/wp-admin/includes/admin-filters.php
+++ b/src/wp-admin/includes/admin-filters.php
@@ -60,7 +60,8 @@ if ( ! is_customize_preview() ) {
 add_action( 'admin_print_scripts', 'print_emoji_detection_script' );
 add_action( 'admin_print_scripts', 'print_head_scripts', 20 );
 add_action( 'admin_print_footer_scripts', '_wp_footer_scripts' );
-add_action( 'admin_print_styles', 'print_emoji_styles' );
+add_action( 'admin_enqueue_scripts', 'wp_enqueue_emoji_styles' );
+add_action( 'admin_print_styles', 'print_emoji_styles' ); // Retained for backwards-compatibility. Unhooked by wp_enqueue_emoji_styles().
 add_action( 'admin_print_styles', 'print_admin_styles', 20 );
 
 add_action( 'admin_print_scripts-index.php', 'wp_localize_community_events' );
diff --git a/src/wp-includes/admin-bar.php b/src/wp-includes/admin-bar.php
index ca35a56ae8..d58e9874ed 100644
--- a/src/wp-includes/admin-bar.php
+++ b/src/wp-includes/admin-bar.php
@@ -1225,32 +1225,51 @@ function wp_admin_bar_add_secondary_groups( $wp_admin_bar ) {
 }
 
 /**
- * Prints style and scripts for the admin bar.
+ * Enqueues inline style to hide the admin bar when printing.
  *
- * @since 3.1.0
+ * @since 6.4.0
  */
-function wp_admin_bar_header() {
-	$type_attr = current_theme_supports( 'html5', 'style' ) ? '' : ' type="text/css"';
-	?>
-<style<?php echo $type_attr; ?> media="print">#wpadminbar { display:none; }</style>
-	<?php
+function wp_enqueue_admin_bar_header_styles() {
+	// Back-compat for plugins that disable functionality by unhooking this action.
+	$action = is_admin() ? 'admin_head' : 'wp_head';
+	if ( ! has_action( $action, 'wp_admin_bar_header' ) ) {
+		return;
+	}
+	remove_action( $action, 'wp_admin_bar_header' );
+
+	wp_add_inline_style( 'admin-bar', '@media print { #wpadminbar { display:none; } }' );
 }
 
 /**
- * Prints default admin bar callback.
+ * Enqueues inline bump styles to make room for the admin bar.
  *
- * @since 3.1.0
+ * @since 6.4.0
  */
-function _admin_bar_bump_cb() {
-	$type_attr = current_theme_supports( 'html5', 'style' ) ? '' : ' type="text/css"';
-	?>
-<style<?php echo $type_attr; ?> media="screen">
-	html { margin-top: 32px !important; }
-	@media screen and ( max-width: 782px ) {
-		html { margin-top: 46px !important; }
+function wp_enqueue_admin_bar_bump_styles() {
+	if ( current_theme_supports( 'admin-bar' ) ) {
+		$admin_bar_args  = get_theme_support( 'admin-bar' );
+		$header_callback = $admin_bar_args[0]['callback'];
 	}
-</style>
-	<?php
+
+	if ( empty( $header_callback ) ) {
+		$header_callback = '_admin_bar_bump_cb';
+	}
+
+	if ( '_admin_bar_bump_cb' !== $header_callback ) {
+		return;
+	}
+
+	// Back-compat for plugins that disable functionality by unhooking this action.
+	if ( ! has_action( 'wp_head', $header_callback ) ) {
+		return;
+	}
+	remove_action( 'wp_head', $header_callback );
+
+	$css = '
+		@media screen { html { margin-top: 32px !important; } }
+		@media screen and ( max-width: 782px ) { html { margin-top: 46px !important; } }
+	';
+	wp_add_inline_style( 'admin-bar', $css );
 }
 
 /**
diff --git a/src/wp-includes/default-filters.php b/src/wp-includes/default-filters.php
index 5add466889..1a20c919d2 100644
--- a/src/wp-includes/default-filters.php
+++ b/src/wp-includes/default-filters.php
@@ -357,7 +357,8 @@ add_action( 'switch_theme', 'wp_clean_theme_json_cache' );
 add_action( 'start_previewing_theme', 'wp_clean_theme_json_cache' );
 add_action( 'after_switch_theme', '_wp_menus_changed' );
 add_action( 'after_switch_theme', '_wp_sidebars_changed' );
-add_action( 'wp_print_styles', 'print_emoji_styles' );
+add_action( 'wp_enqueue_scripts', 'wp_enqueue_emoji_styles' );
+add_action( 'wp_print_styles', 'print_emoji_styles' ); // Retained for backwards-compatibility. Unhooked by wp_enqueue_emoji_styles().
 
 if ( isset( $_GET['replytocom'] ) ) {
 	add_filter( 'wp_robots', 'wp_robots_no_robots' );
@@ -647,6 +648,9 @@ add_action( 'widgets_init', '_wp_block_theme_register_classic_sidebars', 1 );
 // Don't remove. Wrong way to disable.
 add_action( 'template_redirect', '_wp_admin_bar_init', 0 );
 add_action( 'admin_init', '_wp_admin_bar_init' );
+add_action( 'wp_enqueue_scripts', 'wp_enqueue_admin_bar_bump_styles' );
+add_action( 'wp_enqueue_scripts', 'wp_enqueue_admin_bar_header_styles' );
+add_action( 'admin_enqueue_scripts', 'wp_enqueue_admin_bar_header_styles' );
 add_action( 'before_signup_header', '_wp_admin_bar_init' );
 add_action( 'activate_header', '_wp_admin_bar_init' );
 add_action( 'wp_body_open', 'wp_admin_bar_render', 0 );
@@ -668,7 +672,8 @@ add_filter( 'embed_oembed_html', 'wp_maybe_enqueue_oembed_host_js' );
 
 add_action( 'embed_head', 'enqueue_embed_scripts', 1 );
 add_action( 'embed_head', 'print_emoji_detection_script' );
-add_action( 'embed_head', 'print_embed_styles' );
+add_action( 'embed_head', 'wp_enqueue_embed_styles', 9 );
+add_action( 'embed_head', 'print_embed_styles' ); // Retained for backwards-compatibility. Unhooked by wp_enqueue_embed_styles().
 add_action( 'embed_head', 'wp_print_head_scripts', 20 );
 add_action( 'embed_head', 'wp_print_styles', 20 );
 add_action( 'embed_head', 'wp_robots' );
diff --git a/src/wp-includes/deprecated.php b/src/wp-includes/deprecated.php
index c7b284cf5c..a341958a4e 100644
--- a/src/wp-includes/deprecated.php
+++ b/src/wp-includes/deprecated.php
@@ -5871,6 +5871,92 @@ function _wp_theme_json_webfonts_handler() {
 	add_action( 'admin_init', $fn_generate_and_enqueue_editor_styles );
 }
 
+/**
+ * Prints the CSS in the embed iframe header.
+ *
+ * @since 4.4.0
+ * @deprecated 6.4.0 Use wp_enqueue_embed_styles() instead.
+ */
+function print_embed_styles() {
+	_deprecated_function( __FUNCTION__, '6.4.0', 'wp_enqueue_embed_styles' );
+
+	$type_attr = current_theme_supports( 'html5', 'style' ) ? '' : ' type="text/css"';
+	$suffix    = SCRIPT_DEBUG ? '' : '.min';
+	?>
+	<style<?php echo $type_attr; ?>>
+		<?php echo file_get_contents( ABSPATH . WPINC . "/css/wp-embed-template$suffix.css" ); ?>
+	</style>
+	<?php
+}
+
+/**
+ * Prints the important emoji-related styles.
+ *
+ * @since 4.2.0
+ * @deprecated 6.4.0 Use wp_enqueue_emoji_styles() instead.
+ */
+function print_emoji_styles() {
+	_deprecated_function( __FUNCTION__, '6.4.0', 'wp_enqueue_emoji_styles' );
+	static $printed = false;
+
+	if ( $printed ) {
+		return;
+	}
+
+	$printed = true;
+
+	$type_attr = current_theme_supports( 'html5', 'style' ) ? '' : ' type="text/css"';
+	?>
+	<style<?php echo $type_attr; ?>>
+	img.wp-smiley,
+	img.emoji {
+		display: inline !important;
+		border: none !important;
+		box-shadow: none !important;
+		height: 1em !important;
+		width: 1em !important;
+		margin: 0 0.07em !important;
+		vertical-align: -0.1em !important;
+		background: none !important;
+		padding: 0 !important;
+	}
+	</style>
+	<?php
+}
+
+/**
+ * Prints style and scripts for the admin bar.
+ *
+ * @since 3.1.0
+ * @deprecated 6.4.0 Use wp_enqueue_admin_bar_header_styles() instead.
+ */
+function wp_admin_bar_header() {
+	_deprecated_function( __FUNCTION__, '6.4.0', 'wp_enqueue_admin_bar_header_styles' );
+	$type_attr = current_theme_supports( 'html5', 'style' ) ? '' : ' type="text/css"';
+	?>
+	<style<?php echo $type_attr; ?> media="print">#wpadminbar { display:none; }</style>
+	<?php
+}
+
+/**
+ * Prints default admin bar callback.
+ *
+ * @since 3.1.0
+ * @deprecated 6.4.0 Use wp_enqueue_admin_bar_bump_styles() instead.
+ */
+function _admin_bar_bump_cb() {
+	_deprecated_function( __FUNCTION__, '6.4.0', 'wp_enqueue_admin_bar_bump_styles' );
+	$type_attr = current_theme_supports( 'html5', 'style' ) ? '' : ' type="text/css"';
+	?>
+	<style<?php echo $type_attr; ?> media="screen">
+	html { margin-top: 32px !important; }
+	@media screen and ( max-width: 782px ) {
+	  html { margin-top: 46px !important; }
+	}
+	</style>
+	<?php
+}
+
 /**
  * Runs a remote HTTPS request to detect whether HTTPS supported, and stores potential errors.
  *
@@ -5907,4 +5993,4 @@ function wp_update_https_detection_errors() {
 	$support_errors = wp_get_https_detection_errors();
 
 	update_option( 'https_detection_errors', $support_errors );
-}
\ No newline at end of file
+}
diff --git a/src/wp-includes/embed.php b/src/wp-includes/embed.php
index d75939cce6..9e59f1abc0 100644
--- a/src/wp-includes/embed.php
+++ b/src/wp-includes/embed.php
@@ -1059,18 +1059,22 @@ function enqueue_embed_scripts() {
 }
 
 /**
- * Prints the CSS in the embed iframe header.
+ * Enqueues the CSS in the embed iframe header.
  *
- * @since 4.4.0
+ * @since 6.4.0
  */
-function print_embed_styles() {
-	$type_attr = current_theme_supports( 'html5', 'style' ) ? '' : ' type="text/css"';
-	$suffix    = SCRIPT_DEBUG ? '' : '.min';
-	?>
-	<style<?php echo $type_attr; ?>>
-		<?php echo file_get_contents( ABSPATH . WPINC . "/css/wp-embed-template$suffix.css" ); ?>
-	</style>
-	<?php
+function wp_enqueue_embed_styles() {
+	// Back-compat for plugins that disable functionality by unhooking this action.
+	if ( ! has_action( 'embed_head', 'print_embed_styles' ) ) {
+		return;
+	}
+	remove_action( 'embed_head', 'print_embed_styles' );
+
+	$suffix = wp_scripts_get_suffix();
+	$handle = 'wp-embed-template';
+	wp_register_style( $handle, false );
+	wp_add_inline_style( $handle, file_get_contents( ABSPATH . WPINC . "/css/wp-embed-template$suffix.css" ) );
+	wp_enqueue_style( $handle );
 }
 
 /**
diff --git a/src/wp-includes/formatting.php b/src/wp-includes/formatting.php
index 8d6d4341c1..76f77c2a90 100644
--- a/src/wp-includes/formatting.php
+++ b/src/wp-includes/formatting.php
@@ -5858,36 +5858,34 @@ function wp_spaces_regexp() {
 }
 
 /**
- * Prints the important emoji-related styles.
+ * Enqueues the important emoji-related styles.
  *
- * @since 4.2.0
+ * @since 6.4.0
  */
-function print_emoji_styles() {
-	static $printed = false;
-
-	if ( $printed ) {
+function wp_enqueue_emoji_styles() {
+	// Back-compat for plugins that disable functionality by unhooking this action.
+	$action = is_admin() ? 'admin_print_styles' : 'wp_print_styles';
+	if ( ! has_action( $action, 'print_emoji_styles' ) ) {
 		return;
 	}
+	remove_action( $action, 'print_emoji_styles' );
 
-	$printed = true;
-
-	$type_attr = current_theme_supports( 'html5', 'style' ) ? '' : ' type="text/css"';
-	?>
-<style<?php echo $type_attr; ?>>
-img.wp-smiley,
-img.emoji {
-	display: inline !important;
-	border: none !important;
-	box-shadow: none !important;
-	height: 1em !important;
-	width: 1em !important;
-	margin: 0 0.07em !important;
-	vertical-align: -0.1em !important;
-	background: none !important;
-	padding: 0 !important;
-}
-</style>
-	<?php
+	$emoji_styles = '
+	img.wp-smiley, img.emoji {
+		display: inline !important;
+		border: none !important;
+		box-shadow: none !important;
+		height: 1em !important;
+		width: 1em !important;
+		margin: 0 0.07em !important;
+		vertical-align: -0.1em !important;
+		background: none !important;
+		padding: 0 !important;
+	}';
+	$handle       = 'wp-emoji-styles';
+	wp_register_style( $handle, false );
+	wp_add_inline_style( $handle, $emoji_styles );
+	wp_enqueue_style( $handle );
 }
 
 /**
diff --git a/src/wp-includes/theme-templates.php b/src/wp-includes/theme-templates.php
index 2f233ca1d1..3604dc6dbe 100644
--- a/src/wp-includes/theme-templates.php
+++ b/src/wp-includes/theme-templates.php
@@ -118,14 +118,8 @@ function the_block_template_skip_link() {
 	if ( ! $_wp_current_template_content ) {
 		return;
 	}
-	?>
 
-	<?php
-	/**
-	 * Print the skip-link styles.
-	 */
-	?>
-	<style id="skip-link-styles">
+	$skip_link_styles = '
 		.skip-link.screen-reader-text {
 			border: 0;
 			clip: rect(1px,1px,1px,1px);
@@ -154,9 +148,17 @@ function the_block_template_skip_link() {
 			top: 5px;
 			width: auto;
 			z-index: 100000;
-		}
-	</style>
-	<?php
+		}';
+
+	$handle = 'wp-block-template-skip-link';
+
+	/**
+	 * Print the skip-link styles.
+	 */
+	wp_register_style( $handle, false );
+	wp_add_inline_style( $handle, $skip_link_styles );
+	wp_enqueue_style( $handle );
+
 	/**
 	 * Print the skip-link script.
 	 */
diff --git a/tests/phpunit/tests/blocks/editor.php b/tests/phpunit/tests/blocks/editor.php
index f319ace413..0682839605 100644
--- a/tests/phpunit/tests/blocks/editor.php
+++ b/tests/phpunit/tests/blocks/editor.php
@@ -18,6 +18,8 @@ class Tests_Blocks_Editor extends WP_UnitTestCase {
 
 		parent::set_up();
 
+		remove_action( 'wp_print_styles', 'print_emoji_styles' );
+
 		$args = array(
 			'post_title' => 'Example',
 		);
diff --git a/tests/phpunit/tests/oembed/template.php b/tests/phpunit/tests/oembed/template.php
index fca6aadd95..12092ff669 100644
--- a/tests/phpunit/tests/oembed/template.php
+++ b/tests/phpunit/tests/oembed/template.php
@@ -10,6 +10,8 @@ class Tests_Embed_Template extends WP_UnitTestCase {
 
 		global $wp_scripts;
 		$wp_scripts = null;
+
+		remove_action( 'wp_print_styles', 'print_emoji_styles' );
 	}
 
 	public function tear_down() {
diff --git a/tests/phpunit/tests/theme/wpAddGlobalStylesForBlocks.php b/tests/phpunit/tests/theme/wpAddGlobalStylesForBlocks.php
index 02ae7e0253..b009ac7233 100644
--- a/tests/phpunit/tests/theme/wpAddGlobalStylesForBlocks.php
+++ b/tests/phpunit/tests/theme/wpAddGlobalStylesForBlocks.php
@@ -18,6 +18,11 @@ class Tests_Theme_WpAddGlobalStylesForBlocks extends WP_Theme_UnitTestCase {
 	 */
 	private $test_blocks = array();
 
+	public function set_up() {
+		parent::set_up();
+		remove_action( 'wp_print_styles', 'print_emoji_styles' );
+	}
+
 	public function tear_down() {
 		// Unregister test blocks.
 		if ( ! empty( $this->test_blocks ) ) {